Radiator Cap

[Clare Snyder]

Tom Cloud wrote:
> 
> > ....................................................... As for the
> >higher temp thermostats, I believe the reasoning is the higher opening temp
> >makes the water stay in the engine longer in order to absorb more heat from
> >the engine. Use too cool a thermostat and the water doesn't have enough
> >time to leech off enough heat, totally remove the thermostat and you risk
> >actually overheating, not necessarily boiling over but overheating the
> >engine. Water temp doesn't mean a damn thing, it's the block and head temp
> >that counts.
> 
> now, here's where I have a problem -- probably showing just how cirrusly
> uninformed I really am !!  ..... I used to make water-cooled heatsinks.
> Doesn't mean I knew anything.  As long as the water contacts the
> metal, what difference could it possibly make how fast it moves.
> IMHO, this is the most ridiculous line of reasoning I've heard in a
> long time (no offense to you, Chris, ... I assume you're just repeating
> what you've heard or read -- seen it in some radiator ads myself).
> 
> I mean, it's a law of physics that delta-T is required to remove
> heat .... and if you leave the water there, it warms up and then
> doesn't remove as much heat !!!
> 
> I'd like to know .... not really losing sleep over this, but surely there's
> some guru summers that can ease my tortured mind ???  (I mean, I've
> run lots of engines with no thermostat -- always assumed the only problems
> were due to water not getting up into some high places that collect
> air pockets and the engine oil not getting hot quick enough to lube
> at first start.)
> 
> What difference does the rate of flow have to do with heat transfer ??
> Like I said, seems to me that it's totally irrelevant as long as the
> liquid stays in contact with the metal -- in fact, seems t'me that the
> faster the better, since that keeps the delta-T at it's highest !!
> 
> At this point, I pronounce the ads by the rad makers "HOKUM".  Now,
> someone prove me the idiot that most have long suspected  ;-)
> 
> Tom Cloud
> 
>    Warning, dates in calendar are closer than they appear !
Not only does it not absorb enough heat from the engine, it goes through
the rad so fast it doesn't release the heat either. Getting the coolant
up to a high enough temp  gets the temp difference at the rad higher,
allowing the rad to shed more calories or BTUs. This effectively removes
more heat, even if the operating temp is a bit higher. I know it does
not make a lot of sense, but without a restrictor in an engine running
without a stat, overheating of the valve area, for instance, with
resulting head cracks and/or detonation can be a real problem.
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